Phytochromes are red/far-red photoreceptors in plants, which are important to adapt growth and development to the environment. They localise to the cytosol in the dark and translocate into the nucleus in plants exposed to light. Phytochrome interacting factors (PIFs), COP1 and SPA proteins act downstream of phytochromes and actively suppress photomorphogenic development. After transport into the nucleus, light activated phytochromes target PIFs for degradation and inactivate the COP1/SPA complex to promote photomorphogenesis. Understanding how phytochrome nuclear transport is regulated, how it is linked to downstream signalling and how downstream signalling results in regulation of gene expression are major topics in our research.

Phytochromes are ubiquitous in the plant kingdom and also present in green algae, mosses and ferns, i.e. in cryptogams. Both in seed plants and cryptogams the phytochrome families consist of several members, which have overlapping but also specific functions. Using Arabidopsis thaliana and Physcomitrella patens as model systems for seed plants and cryptogams, we also investigate how species-specific light signalling pathways evolved.